1. Field of the Invention
The present invention relates to an improved film cartridge and camera and particularly to a reversible cartridge case and film to provide additional or larger exposures with greater use of the film area and a simplified camera structure.
2. Statement of Prior Art
Present 35mm cameras generally employ film with sprocket holes along the edges which engage a sprocket drive wheel for advancing the film. The film is contained in a single light tight casing with an end being manually secured to a built in take up spool in the camera. After exposure, the film, which has no protective backing, must be rewound onto the supply spool. The sprocket holes make a considerable area of the film unusable and the sprocket wheel causes difficulty in loading, and possible jamming and tearing of the film. Present inexpensive cartridge type cameras employ enclosed cartridges with the film on pre-loaded supply and take up spools. An inner lower opening in the web between the film chambers fits over the camera aperture guide while a small opening on the back displays the exposure number on the film protective backing. This enclosed cartridge allows some loosness or slack in the film over the aperture guide which causes poor resolution.
Use of a camera pressure plate on the back cover to hold the film from a cartridge tightly over an aperture guide has been suggested in U.S. Pat. No. 3,347,142 issued Oct. 17, 1967. The use of two film casings spaced by a rigid member as a magazine, is described in U.S. Pat. No. 3,482,681 issued Dec. 9, 1969. The cartridges, casings and spools, however, are not symmetrical to permit reversal of the film. Use of a reversible film in conjunction with masks to permit doubling of the number of exposures on a film roll or variation of sizes also has previously been suggested in another camera type described in U.S. Pat. No. 3,678,834 of the present inventor, issued July 25, 1972. This concept, however, has not previously been applied to film cartridges which can be used with 35mm single lens reflex type cameras.